I drove 175 miles most of which was highway a few nights ago. I filled up the tank afterwards to check the fuel economy and was extremely disappointed to find that I only got 15 mpg. I was driving the XJ in my signature. Is this normal for a 4.0L or should I start diagnosing?

 

I get around 19-21 on highway if it is flat and steady,it goes down from there depending situation,I think 15 is low ,I would exspect that around town or in the mountains.

 

on the highway through the mountains i can get 18/19 ish. but thats because on the up hills i do like 40 in the truck lane haha. and down the hills get up to speed and coast in N.

 

I recently took a trip to Nevada and managed 15 highway, yeah I know it sucks, but thats not what I bought it for.

 

It's important to note what speed you averaged. Mileage between 55 and 80 varies about 3 or 4 MGP.

 

How do you calculate you mpg?

 

I was doing about 70 mph, with a few miles in town.

 

fill your gas tank, clear your trip odometer.

drive till you're almost on empty.

fill you gas tank, divide the mileage on your trip odometer by the gallons of gas you used to fill your gas tank the second time.

 

Thanks man and love your avatar, SouthPark is amazing. Does a 98 cherokee classic have a trip odometer to where i can reset it without reseting how many miles i have on the engine

 

I can't say for sure, but it should have a trip odometer. No car to my knowledge has the ability to reset the engine mileage, it's against the law to alter odometers in any way, so there's no chance of you reseting it.

 

if there is no trip meter just add one more step and write down the milage before you start then write down the milage after your trip subtract then divide.

 

I think it is as much the driver. If your Jeep is in good tune and such, you should do better than 15. Depends on your gearing, your tires and how much stuff you have hanging on the outside of your XJ.

My 95 ZJ I can get 22 for an average *IF* I work at it. And thats on 31s and 3.73s with 2" over the Upcountry... My 90 XJ gives my daughter 25MPG with the 4.0 and AW4 on 235/75R15s and 3.55s and no lift. Maybe its the John Deere Yellow paint...

 

you drive a brick on wheels. 15 is pretty average.

 

I didn't see where anybody mentioned taking into consideration your larger tire size. Example 31" vs 27" will make a pretty big difference in mileage on your odometer reading if not compensated for, consequently your mileage if this pertains.

 

I have 35's and corrected gauge's so my mileage and mph is right and i get about 15 highway, 14.5/15.